Ion diode design for IBEST

Summary form only given. The IBEST (Ion Beam Surface Treatment) ion diode design is discussed. This diode will be driven by the Sandia RHEPP (Repetitive High Energy Pulsed Power) facility to produce ion beams for IBEST. The diode is based on magnetically-confined anode plasma (MAP) diodes. The diode operates with a magnetically confined anode plasma produced by inductively driven breakdown of an annular localized gas puff. The resulting plasma is confined at the anode side of an annular magnetically insulated diode gap. The first repetitive version of this diode has been operated in bursts at up to 100 Hz repetition rate. The new IBEST diode represents a second-generation MAP diode, and will attempt to make optimal use of several phenomena discovered in the operation of previous MAP diodes. In particular, the standoff distance from the gas puff to the diode gap is reduced by using magnetic nulls to enforce gas breakdown at the desired location directly in front of the inductive driving coils.